Contemporary telecommunications networks may be an amalgam of formerly separate networks that have been merged into a single network, or they may be a single network that must communicate with other types of networks. For example, a packet-switched network, such as an Internet protocol (IP) multimedia subsystem (IMS) network or a next-generation network (NGN), may need to communicate with a circuit-switched network, such as the public switched telephone network (PSTN) or the public land mobile network (PLMN), through gateway nodes. Example gateway nodes include soft switches (SSs), media gateway controllers (MGCs), and signaling gateways (SGWs) that convert signaling messages from one protocol to another protocol. For example, IMS and NGN networks use the session initiation protocol (SIP) for call setup, while PSTN and PLMN networks use signaling system 7 (SS7) for call setup. Thus, signaling gateway nodes may convert signaling messages from SIP protocol to SS7 protocol and vice versa.
Specialized functions have been developed to handle the complexities of the interface between disparate networks. One such function is the breakout gateway control function (BGCF). A BGCF is a function within a packet-switched network, such as an IMS or NGN network, which directs signaling traffic from the packet-switched network in which the BGCF resides into other networks, such as SS7 based networks. The BGCF maintains rules for directing or routing calls between the packet-switched network and a circuit-switched network. A BGCF may communicate with one or more gateway nodes that connect the two networks.
FIG. 1 is a block diagram of a conventional implementation of a merged network having both SS7 and non-SS7 portions. BGCF 100 may be a session initiation protocol (SIP) server that includes routing functionality based on telephone numbers. BGCF 100 communicates with gateway nodes GW1 102 and GW2 104, which connect the non-SS7-based network, such as SIP-based IMS network 106, with the SS7-based network, such as PSTN 108. Because BGCF 100 is a function implemented within the SIP-based network, the SIP-based network is herein referred to as the “internal network” and the SS7-based network is herein referred to as the “external network”. Gateway nodes GW1 102 and GW2 104 may be connected to signaling message routing nodes in the SS7 network, such as signal transfer points (STPs). Here, GW1 102 is connected to STP1 110 and GW2 104 is connected to STP2 112. STP1 110 and STP2 112 are connected to each other and to a pair of end offices (EOs), EO1 114 and EO2 116 in a conventional SS7 topology, in which each STP has a connection to both end offices and to the other STP.
In one example, EO1 114 may service PSTN subscribers having directory numbers in the range 9193800000˜9193809999. Therefore, BGCF 100 may include routing rules that cause signaling for all calls to 919380xxxx to be routed to EO1 114 via GW1 102. It may be desirable to route signaling for all calls to 919380XXXX through GW1 102, for example, because the signaling route via GW1 102 is a lower cost route relative to the signaling route via GW2 104. Similarly, EO2 116 may service PSTN subscribers having directory numbers in the range 9193810000˜9193819999. BGCF 100 may include routing rules that cause signaling for all calls to 919381xxxx to be routed to EO2 116 via GW2 104.
FIG. 1 also illustrates a problem inherent in the conventional implementation of a BGCF. In FIG. 1, the network connection between STP1 110 and EO1 114 has become inoperable, with the result that EO1 114 is unreachable via STP1 110. When STP1 110 detects this fault condition, it may issue a SS7 protocol message, such as the transfer prohibited (TFP) message (FIG. 1, messages 1), to those SS7 signaling points to which STP1 110 is directly connected, in order to inform them that the link between STP1 110 and EO1 114 is down. However, since BGCF 100 is not in the SS7 network, BGCF 100 does not participate in SS7 network management and thus is not aware of the link failure.
Furthermore, BGCF 100 has no information regarding the SS7 network topology and the routing cost structure associated with various potential routes through PSTN 108. In practice, SS7 network conditions are dynamic in nature (due to unexpected network outages, operator initiated outages, changes in route cost structure due to equipment changes or changing service level agreements with network operator partners, etc.) and consequently the least cost route to a particular destination through the SS7 network may vary with time. Since BGCF 100 is not part of the SS7 network PSTN 108, these dynamic variations in SS7 network status and/or underlying route cost structures are not visible to BGCF 100. This shortcoming can lead to significant routing inefficiencies in networking scenarios that involve the use of BGCF nodes to direct traffic into a PSTN or PLMN.
Therefore, BGCF 100 may continue to make traffic routing decisions based on its existing route tables or routing instructions, which may lead to unnecessary congestion and traffic redirection within PSTN 108, IMS network 106, or both. For example, BGCF 100 may be configured to route all signaling messages associated with a DN in the range 919380XXXX to GW1 102, because—unbeknownst to BGCF 100—those DNs are for subscribers associated with EO1 114, and GW1 102 is the least-cost path from BGCF 100 to EO1 114. In the scenario illustrated in FIG. 1, where the link between STP1 110 and EO1 114 is inoperative, a signaling message destined for EO1 114 would continue to be routed from BGCF 100 to GW1 102. Within PSTN 108, the message might travel from GW1 102 to STP1 110, then to STP2 112, and then to EO1 114. Thus, the message would be processed by three nodes (GW1 102, STP1 110, and STP2 112) before arriving at its destination, EO1 114. However, had the message been sent from BGCF 100 to GW2 104 instead of to GW1 102, the message would be processed by only two nodes (GW2 104 and STP2 112) before arriving at EO1 114.
Accordingly, in light of these disadvantages associated with conventional implementations of merged networks, there exists a need for a mechanism for communicating information from an SS7 based network to a non-SS7 based network so that the non-SS7 based network can efficiently route signaling traffic into the SS7 based network. Specifically, there exists a need for methods, systems, and computer readable media for managing the flow of signaling traffic entering a SS7-based network.